# CON-042 — The phone field must be optional on a general-purpose form

> On a form that exists for something other than SMS signup, the phone-number field must not be required to submit.

- **Rule ID:** CON-042
- **Layer:** Consent flow (`CONSENT_FLOW`)
- **Checks:** `opt-in form phone field required attribute`
- **Severity:** HIGH — Rejected by at least one carrier or provider, and a common cause of failure at the rest.
- **When it bites:** Gates approval — get this wrong and registration is refused
- **How it is detected:** AI judgement over the crawled website or policy page
- **Fix type:** Fix the website — no form edit clears it
- **Required by:** Bandwidth, Telnyx, Twilio
- **Applies:** Applies when consent was collected by web form, account settings and third party.
- **Canonical URL:** https://ekas.io/rules/10dlc/consent-flow/con-042/

## Why this rule exists

A required number on a contact or quote form takes the number as the price of the enquiry, and everything downstream treats that as a collected lead rather than an opt-in. Bandwidth states it flatly — phone numbers cannot be a required field on the website where opt-in is collected — because a number given under compulsion cannot be told apart later from one given willingly.

## How to fix it

Drop the required attribute and the asterisk from the phone input on any form whose purpose is not SMS signup, and confirm the form submits without it. Done when a visitor can send you an enquiry giving only an email address.

## Common mistakes

- A form whose entire purpose IS SMS signup may require the number — the field is the point of the form, and this rule does not apply to it.

## Provider rejection codes

| Provider | Code | Resubmission allowed |
| --- | --- | --- |
| Twilio (gen2) | `30931` | yes |
| Twilio (gen2) | `30923` | yes |

## Notes

DIVERGENCE, canonical form taken: Bandwidth forbids a required phone field outright; Telnyx and the website-evidence research allow one provided the SMS consent control is itself optional. The strict-superset rule takes Bandwidth, so this fires wherever the form has another purpose. Where the phone field genuinely must stay required for that purpose, CON-043 and CON-044 are the rules that make it survivable.